It is estimated that cancer ends a human life every minute in the United States, and that more than three million others currently suffer from some form of the disease. Among women, breast cancer is the second most common cancer and the leading cause of cancer deaths.

After menopause, many women use hormone replacement therapy (HRT) to compensate for the body's natural decline in hormone production. However, as a study in the Journal of the American Medical Association suggests, the risks associated with HRT use may outweigh the benefits.

As part of a nationwide breast cancer screening program called the Breast Cancer Detection Demonstration Project, 46,355 postmenopausal women were evaluated for duration and type of hormone use and monitored for the incidence of breast cancer. Of particular interest was the influence of estrogen, progestin, or a combination of the two hormones on the risk of developing the disease.

During the 15-year study, 2,082 cases of breast cancer were identified. Women taking the progestin-estrogen combination were at higher risk for the disease than women taking estrogen alone, and this risk increased more rapidly in the combination therapy group vs. the estrogen group per year of use.

The authors note that their data suggest that "the estrogen-progestin regimen increases breast cancer risk beyond that associated with estrogen alone." Talk to your doctor about the risks and benefits associated with hormone replacement therapy.